Magnetoresistive (MR) read sensors are used in magnetic disk and tape systems to read signals in the form of changes in magnetic flux. Generally, MR read sensors are fabricated as multi-layered structures in which thin film layers are deposited on a substrate. U.S. Pat. No. 5,508,866 to Gill, et al. discloses such an MR sensor having a nickel oxide material that is antiferromagnetic and is an electrical insulator, the material being placed between a substrate and a soft adjacent layer (SAL). The prior art patented structure is shown in FIG. 1. The MR sensor comprises an antiferromagnetic (AFM) stabilization layer (101) of nickel oxide (NiO), a transverse bias layer (102) of nickel-iron-niobium (NiFeNb) called a soft adjacent layer (SAL), a spacer layer (103) of tantalum (Ta), and an MR layer (105) of nickel iron (NiFe) deposited on a suitable substrate (111). A longitudinal bias layer (107) of nickel manganese (NiMn) is deposited over a seed layer (104) of NiFe in the passive end or tail regions (106) of the sensor to provide a longitudinal bias field in the MR layer (105) by exchange coupling between the NiMn and the NiFe layers. Conductive leads (109) of a suitable low resistivity material are formed in the end regions over the longitudinal bias layer to provide electrical connection between the MR sensor and external circuitry. The conductive lead (109) is a layered structure including a primary conductor of gold (Au) with an overlayer and underlayer of Ta. Additionally, the MR layer (105) is capped with a thin capping layer (113) of Ta in the sensor's active region. The electrical lead connectors connect the MR sensor to a signal sensing circuit (114) and a bias current source (116).
While oxide-based antiferromagnetic materials result in improved corrosion properties, an oxide based pinned SAL has a small pinning field.
It is therefore desirable to provide an improved MR read sensor having a pinning field that is much larger than the pinning field achieved by MR heads with an oxide based antiferromagnet.
It is also desirable to provide a method for fabricating an improved MR read sensor having a pinning field that is much larger than the pinning field achieved by MR heads with an oxide antiferromagnet.